_radius = 10
PI = 3.1415926

def area(radius):
    return PI * radius * radius
def circumference(radius):
    return 2 * PI * radius
def main():
    print("半径为%d的圆面积是%f" % (_radius, area(_radius)))
    print("半径为%d的圆周长是%f" % (_radius, circumference(_radius)))
if __name__ == '__main__':
    main()